Transitioning from First Drug Use to Dependence Onset: Illustration of a Multiparametric Approach for Comparative Epidemiology

Short-chain fatty acid valerate reduces voluntary alcohol intake in male mice

BACKGROUND

Despite serious health and social consequences, effective intervention strategies for habitual alcohol binge drinking are lacking. The development of novel therapeutic and preventative approaches is highly desirable. Accumulating evidence in the past several years has established associations between the gut microbiome and microbial metabolites with drinking behavior, but druggable targets and their underlying mechanism of action are understudied.

RESULTS

Here, using a drink-in-the-dark mouse model, we identified a microbiome metabolite-based novel treatment (sodium valerate) that can reduce excessive alcohol drinking. Sodium valerate is a sodium salt of valeric acid short-chain fatty acid with a similar structure as γ-aminobutyric acid (GABA). Ten days of oral sodium valerate supplementation attenuates excessive alcohol drinking by 40%, reduces blood ethanol concentration by 53%, and improves anxiety-like or approach-avoidance behavior in male mice, without affecting overall food and water intake. Mechanistically, sodium valerate supplementation increases GABA levels across stool, blood, and amygdala. It also significantly increases H4 acetylation in the amygdala of mice. Transcriptomics analysis of the amygdala revealed that sodium valerate supplementation led to changes in gene expression associated with functional pathways including potassium voltage-gated channels, inflammation, glutamate degradation, L-DOPA degradation, and psychological behaviors. 16S microbiome profiling showed that sodium valerate supplementation shifts the gut microbiome composition and decreases microbiome-derived neuroactive compounds through GABA degradation in the gut microbiome.

CONCLUSION

Our findings suggest that sodium valerate holds promise as an innovative therapeutic avenue for the reduction of habitual binge drinking, potentially through multifaceted mechanisms. Video Abstract.

Compulsivity and Inhibitory Control Deficits in Abstinent Individuals With Heroin Addiction and Their Biological Siblings Compared With Unrelated Healthy Control Participants

BACKGROUND

Compulsivity represents the performance of persistent and repetitive acts despite negative consequences and is considered one of the critical mechanisms for drug addiction. Although compulsivity-related neurocognitive impairments have been linked to addiction, it remains unclear whether these deficits might have predated drug abuse as potential familial susceptibilities.

METHODS

A large sample of 213 adult participants were recruited, including 70 abstinent individuals addicted to heroin (HAs), 69 unaffected biological siblings of the HAs (siblings), and 74 unrelated healthy control participants. Compulsivity-related neurocognitive functions were evaluated using the intradimensional/extradimensional set-shift task and a probabilistic reversal learning task. Compulsive traits were measured by the Obsessive-Compulsive Inventory-Revised. Inhibitory control was assessed using the stop signal task and Stroop Color and Word Test. Network models for group recognition were conducted using multilayer perceptron neural networks.

RESULTS

Data indicated that both HAs and siblings performed worse than healthy control participants on compulsivity-related aspects (i.e., shifting and reversal learning functions) and inhibitory control and had higher levels of self-reported compulsive traits. Furthermore, neural models revealed that a possible 3-facet clustering of neurocognitive deficits was linked to both HAs and siblings.

CONCLUSIONS

Our findings suggest that deficits in shift reversal and inhibitory control aspects and elevated compulsive traits, shared by HAs and their unaffected siblings, may putatively represent conceivable markers associated with familial vulnerabilities implicated in the development of heroin dependence.

Rapid nongenomic estrogen signaling controls alcohol drinking behavior

The sex steroid hormone estrogen is a key modulator of numerous physiological processes and adaptive behaviors, but it may also be co-opted to drive maladaptive behaviors. While many behavioral roles for estrogen signaling have been shown to occur through canonical genomic signaling mechanisms via nuclear receptors, estrogen can also act in a neurotransmitter-like fashion at membrane-associated estrogen receptors to rapidly regulate neuronal function. Early alcohol drinking confers greater risk for alcohol use disorder in women than men, and binge alcohol drinking is correlated with high circulating estrogen but a causal role for estrogen in alcohol drinking has not been established. Here, we demonstrate that gonadally intact female mice consume more alcohol and display an anxiolytic phenotype when they have elevated levels of ovarian-derived estrogen across the estrous cycle. We found that rapid, nongenomic estrogen signaling at membrane-associated estrogen receptor alpha in the bed nucleus of the stria terminalis (BNST) is necessary and sufficient for the pro-alcohol drinking effects of ovarian estrogen signaling, regardless of the transcriptional program of a high ovarian estrogen state. We further show that a population of corticotropin-releasing factor (CRF) BNST neurons (BNSTCRF) is a critical mediator of these effects, as high estrogen rapidly enhances synaptic excitation of BNSTCRF neurons and promotes their role in driving binge alcohol drinking. These findings show a causal role for endogenous, ovarian-derived estrogen in hormonal modulation of risky alcohol consumption and provide the first demonstration of a purely rapid, nongenomic signaling mechanism of ovarian estrogen in the brain controlling behavior in gonadally intact females.

Sex differences in binge alcohol drinking and the behavioral consequences of protracted abstinence in C57BL/6J mice

BACKGROUND

Binge alcohol drinking is a risk factor linked to numerous disease states including alcohol use disorder (AUD). While men binge drink more alcohol than women, this demographic gap is quickly shrinking, and preclinical studies demonstrate that females consistently consume more alcohol than males. Further, women are at increased risk for the co-expression of AUD with neuropsychiatric diseases such as anxiety and mood disorders. However, little is understood about chronic voluntary alcohol drinking and its long-term effects on behavior. Here, we sought to characterize sex differences in chronic binge drinking and the effects of protracted alcohol abstinence on anxiety- and affective-related behaviors in males and females.

METHODS

We assessed binge alcohol drinking patterns in male and female C57BL/6J mice using a modified Drinking in the Dark (DID) paradigm in which mice received home cage access to one bottle of 10% or 20% alcohol (EtOH) or water for 2 h per day on Days 1-3 and to two bottles (EtOH/H2O + H2O) for 24 h on Day 4 for 8 weekly cycles. Mice were then tested for the effects of protracted abstinence on avoidance, affective, and compulsive behaviors.

RESULTS

Female mice consumed more alcohol than males consistently across cycles of DID and at 2, 4, and 24-h timepoints within the day, with a more robust sex difference for 20% than 10% EtOH. Females also consumed more water than males, an effect that emerged at the later time points; this water consumption bias diminished when alcohol was available. Further, while increased alcohol consumption was correlated with decreased water consumption in males, there was no relationship between these two measures in females. Alcohol preference was higher in 10% vs. 20% EtOH for both sexes. During protracted abstinence following chronic binge drinking, mice displayed decreased avoidance behavior (elevated plus maze, open field, novelty suppressed feeding) and increased compulsive behavior (marble burying) that was especially robust in females. There was no effect of alcohol history on stress coping and negative affective behaviors (sucrose preference, forced swim test, tail suspension) in either sex.

CONCLUSION

Female mice engaged in higher volume binge drinking than their male counterparts. Although females also consumed more water than males, their higher alcohol consumption was not driven by increased total fluid intake. Further, the effects of protracted abstinence following chronic binge drinking was driven by behavioral disinhibition that was more pronounced in females. Given the reciprocal relationship between risk-taking and alcohol use in neuropsychiatric disease states, these results have implications for sex-dependent alcohol drinking patterns and their long-term negative neuropsychiatric/physiological health outcomes in humans.

Sex differences in binge alcohol drinking and the behavioral consequences of protracted abstinence in C57BL/6J mice

Background

Binge alcohol drinking is a risk factor linked to numerous disease states including alcohol use disorder (AUD). While men binge drink more alcohol than women, this demographic gap is quickly shrinking, and preclinical studies demonstrate that females consistently consume more alcohol than males. Further, women are at increased risk for the co-expression of AUD with neuropsychiatric diseases such as anxiety and mood disorders. However, little is understood about chronic voluntary alcohol drinking and its long-term effects on behavior. Here, we sought to characterize sex differences in chronic binge drinking and the effects of protracted alcohol abstinence on anxiety- and affective-related behaviors in males and females.

Methods

We assessed binge alcohol drinking patterns in male and female C57BL/6J mice using a modified Drinking in the Dark (DID) paradigm in which mice received home cage access to one bottle of 10% or 20% alcohol (EtOH) or water for 2 hrs per day on Days 1-3 and to two bottles (EtOH/H2O + H2O) for 24 hrs on Day 4 for eight weekly cycles. Mice were then tested for the effects of protracted abstinence on avoidance, affective, and compulsive behaviors.

Results

Female mice consumed more alcohol than males consistently across cycles of DID and at 2, 4, and 24-hr timepoints within the day, with a more robust sex difference for 20% than 10% EtOH. Females also consumed more water than males, an effect that emerged at the later time points; this water consumption bias diminished when alcohol was available. Further, while increased alcohol consumption was correlated with decreased water consumption in males, there was no relationship between these two measures in females. Alcohol preference was higher in 10% vs. 20% EtOH for both sexes. During protracted abstinence following chronic binge drinking, mice displayed decreased avoidance behavior (elevated plus maze, open field, novelty suppressed feeding) and increased compulsive behavior (marble burying) that was especially robust in females. There was no effect of alcohol history on stress coping and negative affective behaviors (sucrose preference, forced swim test, tail suspension) in either sex.

Conclusion

Female mice engaged in higher volume binge drinking than their male counterparts. Although females also consumed more water than males, their higher alcohol consumption was not driven by increased total fluid intake. Further, the effects of protracted abstinence following chronic binge drinking was driven by behavioral disinhibition that was more pronounced in females. Given the reciprocal relationship between risk-taking and alcohol use in neuropsychiatric disease states, these results have implications for sex-dependent alcohol drinking patterns and their long-term negative neuropsychiatric/physiological health outcomes in humans.

Delay discounting as a behavioral phenotype associated with social rank in female and male cynomolgus monkeys: Correlation with kappa opioid receptor availability

Cocaine use disorder (CUD) is a significant problem worldwide, with no FDA-approved treatments. Epidemiological data indicate that only about 17 % of people that use cocaine will meet DSM criteria for CUD. Thus, the identification of biomarkers predictive of eventual cocaine use may be of great value. Two potentially useful predictors of CUD are social hierarchies in nonhuman primates and delay discounting. Both social rank and preference for a smaller, immediate reinforcer relative to a larger, delayed reinforcer have been predictive of CUD. Therefore, we wanted to determine if there was also a relationship between these two predictors of CUD. In the present study, monkeys cocaine-naive responded under a concurrent schedule of 1- vs. 3-food pellets and delivery of the 3-pellet option was delayed. The primary dependent variable was the indifference point (IP), which is the delay that results in 50 % choice for both options. In the initial determination of IP, there were no differences based on sex or social rank of the monkeys. When the delays were redetermined after ~25 baseline sessions (range 5-128 sessions), dominant females and subordinate males showed the largest increases in IP scores from the first determination to the second. Because 13 of these monkeys had prior PET scans of the kappa opioid receptor (KOR), we examined the relationship between KOR availability and IP values and found that the change in IP scores from the first to the second determination significantly negatively predicted average KOR availability in most brain regions. Future studies will examine acquisition to cocaine self-administration in these same monkeys, to determine if IP values are predictive of vulnerability to cocaine reinforcement.

Compulsive drug-taking is associated with habenula-frontal cortex connectivity

As a critical node connecting the forebrain with the midbrain, the lateral habenula (LHb) processes negative feedback in response to aversive events and plays an essential role in value-based decision-making. Compulsive drug use, a hallmark of substance use disorder, is attributed to maladaptive decision-making regarding aversive drug-use-related events and has been associated with dysregulation of various frontal-midbrain circuits. To understand the contributions of frontal-habenula-midbrain circuits in the development of drug dependence, we employed a rat model of methamphetamine self-administration (SA) in the presence of concomitant footshock, which has been proposed to model compulsive drug-taking in humans. In this longitudinal study, functional MRI data were collected at pretraining baseline, after 20 d of long-access SA phase, and after 5 d of concomitant footshock coupled with SA (punishment phase). Individual differences in response to punishment were quantified by a "compulsivity index (CI)," defined as drug infusions at the end of punishment phase, normalized by those at the end of SA phase. Functional connectivity of LHb with the frontal cortices and substantia nigra (SN) after the punishment phase was positively correlated with the CI in rats that maintained drug SA despite receiving increasing-intensity footshock. In contrast, functional connectivity of the same circuits was negatively correlated with CI in rats that significantly reduced SA. These findings suggest that individual differences in compulsive drug-taking are reflected by alterations within frontal-LHb-SN circuits after experiencing the negative consequences from SA, suggesting these circuits may serve as unique biomarkers and potential therapeutic targets for individualized treatment of addiction.

Sex differences in brain regional homogeneity during acute abstinence in cocaine use disorder

There are significant sex differences in the clinical characteristics of cocaine use disorder (CUD). As this is a brain disorder that involves changes in functional connectivity, we investigated the existence of sex differences among people with CUD and controls. We used a data‐driven method comparing males (n = 20, CK‐M) and females with CUD (n = 20, CK‐F) and healthy controls (20 males, HC‐M and 20 females, HC‐F). The participants undertook a resting‐state functional magnetic resonance imaging exam. Regional homogeneity (ReHo) was performed to identify group and sex differences. Persons with CUD of both sexes presented lower ReHo parameters than controls, especially within the parietal lobule. Males with CUD showed higher ReHo than females in three right‐side brain areas: postcentral gyrus, putamen and fusiform gyrus. It was found that abstinence symptoms severity was associated with lower ReHo values in the right postcentral gyrus and the right fusiform gyrus. Participants with CUD exhibited altered ReHo parameters compared to controls, similar to what is found in ageing‐related disorders. Our data also indicate that cocaine has sex‐specific effects on brain functioning when analysing ReHo.

Onset of alcohol use disorder among alcohol initiates by race/ethnicity

Prevalence of alcohol use disorders (AUD) varies across racial/ethnic groups. It remains unclear whether rapid transition from first-time alcohol use to developing AUD varies by race and ethnicity. In this study, we investigate racial/ethnic differences in AUD onset among first-time alcohol drinkers and identify specific predictors of AUD onset by racial/ethnic group. The study population was non-institutionalized US residents aged 12 and older. Within four nationally representative probability samples (n ∼70,000/year) drawn from the 2015-2018 National Surveys on Drug Use and Health, we identified 9,381 individuals who initiated alcohol use within 1-12 months prior to the survey. The probability of AUD after initiation was estimated for the entire sample, followed by racial/ethnic group stratification. Bivariate and multivariable logistic regression models were used to identify predictors of AUD onset among alcohol initiates. The overall incidence estimate of AUD among alcohol initiates was 3.7% (95% CI = 3.0%, 4.6%). There was no significant variation in the incidence of AUD between racial/ethnic groups. Drug use, drug use disorders, and major depressive episode were significant predictors of AUD onset among all alcohol initiates. However, these predictors were not significant among non-Hispanic/Latinx Black individuals. Drug use and drug use disorders were strong predictors of AUD onset among alcohol initiates, except among non-Hispanic/Latinx Black individuals. These findings strengthen the importance of focusing on the co-use of alcohol and other drugs and the need to further investigate the risk profile differences between racial/ethnic groups.

Cocaine and Marijuana Polysubstance Use and Cocaine Use Disorder: Investigating Mediated Effects through Patterns of Cocaine Use

Cocaine use is on the rise and it is comorbid with marijuana use. We examined the association between lifetime cocaine + marijuana polysubstance use (CM PSU) versus cocaine only and lifetime cocaine use disorder (CocUD) and examined the potential mediation by cocaine use patterns. Methods: A total of 2,968 lifetime cocaine users were identified from the National Epidemiologic Survey on Alcohol and Related Conditions-III. Mediation analysis was utilized to examine cocaine use quantity, frequency, and duration as potential mediators in the association between CM PSU and CocUD. A parallel multiple mediator model and a structural equation model were used, respectively, to examine: (1) the individual contribution of cocaine use quantity, frequency, and duration, and (2) combined contribution as a set specified by a latent variable. Results: Cocaine users were divided into 2,782 (93.7%) CM polysubstance users and 186 (6.3%) cocaine only users. CM PSU was associated with decreased risk of CocUD, but after including the mediators, the association was no longer significant. Examined separately, only quantity was found to be a significant mediator over and above frequency and duration, while the latent variable with three cocaine use pattern indicators explained 56.6% of the total association between CM PSU and CocUD. Conclusions: Compared to cocaine only users, CM polysubstance users were less likely to use cocaine heavily; this lower intensity of cocaine use was in turn associated with decreased risk of CocUD. Future research is warranted to determine the nature of the association between CM PSU and reduced CocUD.

Identification of Typologies of Cocaine Use Based on Quantity, Frequency, and Duration of Use: A Latent Profile Analysis

OBJECTIVES

We identified the patterns of cocaine use during individuals' heaviest use period by considering quantity, frequency, and duration simultaneously and examined the correlates and risk profile for these patterns.

METHODS

Latent profile analysis was conducted among the 3117 individuals who reported lifetime use of cocaine in the National Epidemiologic Survey on Alcohol and Related Conditions-III (NESARC-III) with quantity, frequency, and duration used as indicators. Logistic regression analyses examined factors associated with subtype membership based on patterns of cocaine use and the relationships between these patterns and cocaine use disorder (CocUD) and its severity.

RESULTS

Four patterns were identified: a "low use" class (72.6%), a "moderate use" class (8.2%), a "daily use" class (17.9%), and a "very high quantity use" class (1.3%). Relative to non-Hispanic White and the "low use" class, non-Hispanic Black was associated with increased odds to be in the "moderate use" and "daily use" classes. Higher prevalence of smoking crack cocaine and poly-route use was observed among the "very high quantity use" class relative to other classes; increased risk of using other substances was associated with the "daily use" class. Higher levels of cocaine use were associated with higher risks of CocUD and worse severity compared to the "low use" class.

CONCLUSIONS

People who use cocaine are heterogeneous with different patterns of use and risks of CocUD. Reducing cocaine smoking and poly-route of use should be placed as the same priority as decreasing very high quantity of use in interventions.

The association between quantity, frequency and duration of cocaine use during the heaviest use period and DSM-5 cocaine use disorder

BACKGROUND

Quantity (Q), frequency (F), and duration (D) of cocaine use during a person's heaviest use period are important aspects of cocaine use patterns that associated with cocaine use disorder (CocUD).

METHODS

A total 2988 lifetime cocaine users who met CocUD after the onset of cocaine heaviest use were identified from the National Epidemiologic Survey on Alcohol and Related Conditions-III (NESARC-III). QFD were each categorized into four levels. Hierarchical regressions were used to examine the association between QFD of cocaine use and CocUD. Two-way interactions between QFD were also examined.

RESULTS

As the level of cocaine use increased from low to very high, the prevalence of CocUD increased. Compared to people with low F, cocaine users with very high F were 12.09 times (95 %CI 6.33, 23.07) as likely to meet criteria for CocUD. Similarly, Q was associated with 4.84 (95 %CI 2.55, 9.18) times the risk of CocUD. D was not significantly associated with the risk of CocUD. Significant additive interaction was identified between Q*F on CocUD prevalence. Approximately one-third of the excess risk associated with having high Q & high F was due to the interactive effect.

CONCLUSION

Of these three cocaine use patterns, F had the strongest association with CocUD, followed by the Q. High Q and high F was a very dangerous pattern of cocaine use as the combination had as a synergistic effect on the risk of CocUD. It is important for intervention programs to focus on the reduction of both Q and F.

Accelerated development of cocaine-associated dopamine transients and cocaine use vulnerability following traumatic stress

Post-traumatic stress disorder and cocaine use disorder are highly co-morbid psychiatric conditions. The onset of post-traumatic stress disorder generally occurs prior to the development of cocaine use disorder, and thus it appears that the development of post-traumatic stress disorder drives cocaine use vulnerability. We recently characterized a rat model of post-traumatic stress disorder with segregation of rats as susceptible and resilient based on anxiety-like behavior in the elevated plus maze and context avoidance. We paired this model with in vivo fast scan cyclic voltammetry in freely moving rats to test for differences in dopamine signaling in the nucleus accumbens core at baseline, in response to a single dose of cocaine, and in response to cocaine-paired cues. Further, we examined differences in the acquisition of cocaine self-administration across groups. Results indicate that susceptibility to traumatic stress is associated with alterations in phasic dopamine signaling architecture that increase the rate at which dopamine signals entrain to cocaine-associated cues and increase the magnitude of persistent cue-evoked dopamine signals following training. These changes in phasic dopamine signaling correspond with increases in the rate at which susceptible rats develop excessive cocaine-taking behavior. Together, our studies demonstrate that susceptibility to traumatic stress is associated with a cocaine use-vulnerable phenotype and suggests that differences in phasic dopamine signaling architecture may contribute to the process by which this vulnerability occurs.

Cocaine dependence: "Side effects" and syndrome formation within 1-12 months after first cocaine use

BACKGROUND

This project offers new epidemiological estimates for DSM-IV cocaine dependence among sub-groups of newly incident cocaine users in the United States (US), including estimated attack rates for 21 dependence-related cocaine side effect problems and experiences occurring <12 months after onset.

METHOD

In 2002-2016, US National Surveys on Drug Use and Health (NSDUH) sampled, recruited, and assessed cocaine experiences of non-institutionalized civilians. Unweighted estimates for year-pairs (2002-3,…,2015-16) are from 3488 cocaine powder-only initiates and 275 powder-then-crack initiates (all evaluated <12 months after onset). Analysis-weighted attack rate estimates are incidence proportions with 95% confidence intervals (CI), summarized via meta-analysis.

RESULTS

Evaluated <12 months after onset, meta-analysis summaries show 5% of powder-only initiates developed cocaine dependence (95% CI = 4%, 6%) versus 22% of powder-then-crack initiates (95% CI = 17%, 29%). For several cocaine side effect problems and experiences (e.g., 'loss of control' indicators) there is a statistically robust crack-associated excess risk.

CONCLUSIONS

Three interpretations of observed crack-associated excess risk are especially cogent and deserving of continued inquiry: (1) Powder-then-crack initiates start with heightened dependence risk susceptibilities (i.e., pre-dating onset); (2) Powder-using initiates become cocaine dependent and then start using crack; (3) The cocaine delivery variant of 'crack-smoking' is more toxic than powder insufflation. For powder-then-crack initiates, the cocaine dependence risk (22%) is modestly lower but statistically undifferentiable from a recently estimated risk of heroin dependence <12 months after heroin onset (30%). Clinicians can use these side effect estimates in an evidence-based diagnostic workup when patients disclose new onsets of cocaine use.

Female-male differences in prescription pain reliever dependence levels: Evidence on newly incident adolescent and young adult users in the United States, 2002-2014

BACKGROUND

A comprehensive epidemiology of dependence on prescription opioid pain relievers requires evidence about age-specific female-male differences, possibly manifest during adolescent and early adult years. In this study, we identified newly incident extra-medical users of prescription pain relievers (EMPPR), all observed with onsets before the 22nd birthday. We then quantified female-male differences in clinical features or manifestations of opioid dependence (OD), devised a measurement-equivalent OD dimension, and estimated age-specific female-male differences in OD levels.

METHOD

The population under study included 12-to-21-year-old non-institutionalized civilian community residents of United States sampled for recent nation-scale surveys. Confidential computer-assisted self-interviews identified newly incident EMPPR users (n = 10,188). Analysis-weighted estimation procedures yielded cumulative incidence proportions for each OD feature, evaluated measurement non-equivalence across subgroups, and estimated female-male differences age-by-age.

RESULTS

(1) Tolerance and salience ('spending a lot of time') are most common OD features. (2) Measurement non-equivalence (bias) was found across sex- and onset-age groups. (3) With biasing features removed, we can see elevated OD levels for female new initiates, age-by-age. Subsidiary analyses suggested possibly accelerated progression toward higher OD levels when extra-medical PPR use starts before age 18.

CONCLUSIONS

Dimensional approaches to OD and other drug use disorders have gained popularity but can be fragile when differential measurement biases are left uncontrolled. This study's bias-corrected dimensional view of female-male differences shows elevated OD levels among newly incident female EMPPR users relative to new male initiates. Future studies can check for accelerated progression to higher OD levels when EM use starts before age 18 years.

Drugs of Abuse Induced-Subversion of the Peripheral Immune Response and Central Glial Activity: Focus on Novel Therapeutic Approaches

BACKGROUND

Drugs of abuse affect both central nervous system (CNS) and peripheral immune function. Besides the involvement of dopamine and glutamate systems, chronic exposure to drugs of abuse alters immune homeostasis, promoting a pro-inflammatory status. At the same time, impaired peripheral immunity leads to an increased susceptibility to infections in drug abusers.

DISCUSSION

There is evidence that certain drugs, such as opioids, activate microglial cells and astrocytes which, in turn, provoke central neuroinflammation. Particularly, opioids bind the Toll-like receptor (TLR)-4 with increased expression of nuclear factor kappa-light-chain-enhancer of activated B cells and release of pro-inflammatory cytokines. Peripheral mediators released by immune cells also contribute to aggravate central neuroinflammation.

CONCLUSION

These are based either on the inhibition of TLR-4 activation by drugs of abuse or on the correction of dopamine and glutamate pathways. Finally, a hypothetic nutraceutical intervention with polyphenols in view of their anti-inflammatory and anti-oxidant properties will be outlined as an adjuvant treatment for drugs of abuse-related disorders.

Sex-based differences in multidimensional clinical assessments of early-abstinence crack cocaine users

Crack cocaine use disorder (CUD) has been related to sex differences. This work aimed to compare the severity of drug use and the severity of other negative related outcomes in males and females with CUD. A total of 1344 inpatients (798 males and 546 females) with crack cocaine use disorder (CUD) were evaluated by a detailed multidimensional clinical assessment, including addiction severity and trauma exposure. Linear regression predicted higher drug use severity (β = 0.273, p < 0.001) and more problems in domains related to childcare issues (β = 0.321), criminal involvement (β = 0.108), work-related problems (β = 0.281) and social support impairments (β = 0.142) for females, all with p < 0.001. Alcohol problems were predicted to be higher in males (β = -0.206, P < 0.001). Females had higher rates of other mental disorders, particularly trauma and stress-related disorders (OR: 3.206, CI: 2.22, 4.61). Important sex differences also emerged in trauma history and HIV infection prevalence. CUD has a more severe clinical presentation among females facing early abstinence. Sex differences in the CUD course indicate the need for consideration of sex-specific interventions and research.

The Molecular Basis of Drug Addiction: Linking Epigenetic to Synaptic and Circuit Mechanisms

Addiction is a disease in which, after a period of recreational use, a subset of individuals develops compulsive use that does not stop even in light of major negative consequences. Here, we review the evidence for underlying epigenetic remodeling in brain in two settings. First, excessive dopamine signaling during drug use may modulate gene expression, altering synaptic function and circuit activity and leading over time to maladaptive behaviors in vulnerable individuals. Second, on a longer timescale, life experience can shape the epigenetic landscape in brain and thereby may contribute to an individual's vulnerability by amplifying drug-induced changes in gene expression that drive the transition to addiction. We conclude by exploring how epigenetic mechanisms might serve as therapeutic targets for addiction treatments.

Underage drinking, alcohol dependence, and young people starting to use prescription pain relievers extra-medically: A zero-inflated Poisson regression model

Among young people who start using prescription pain relievers (PPRs) for feeling-states such as "to get high" or otherwise beyond boundaries intended by prescribers, the most recent epidemiological incidence estimates show 2%-9% with rapid-onset opioid dependence. In this work, we study recently active underage alcohol dependence as a susceptibility marker and estimate alcohol dependence-associated PPR rates of use, once use starts. In recent U.S. epidemiological samples, we identified 16,125 community-dwelling 12-to-20-year-olds with standardized assessments of both problem drinking and newly incident extra-medical PPR use. We applied zero-inflated Poisson (ZIP) regressions to estimate (a) alcohol dependence associations with susceptibility-to-persist after the very first occasion of extra-medical PPR use, and (b) the rate of PPR use, conditional on persistence. Underage drinkers with alcohol dependence were more susceptible to persistence in their extra-medical PPR use (p < .001). In addition, given susceptibility-to-persistence, there was an alcohol dependence-associated excess rate of extra-medical PPR use (risk ratio = 1.3; 95% confidence interval = 1.1, 1.6). Using ZIP regressions, we can see that underage alcohol dependence signals membership in a susceptible-to-persistence class of extra-medical PPR users and excess rates of extra-medical use. Underage drinking can be an indicator of greater vulnerability to start and persist in extra-medical use of PPR, particularly if presenting clinical features of alcohol dependence already are seen at or near time of first onset of such PPR use. For alcohol dependence-affected adolescent patients, nondrug pain management plans deserve consideration, with special surveillance if analgesic drugs are prescribed. Implications for genetic susceptibility research are discussed. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Conditional probabilities of substance use disorders and associated risk factors: Progression from first use to use disorder on alcohol, cannabis, stimulants, sedatives and opioids

BACKGROUND

Relatively little is known about factors that may lead to the development of a substance use disorder (SUD), across a range of drug classes. This study aimed to identify factors that predict the likelihood of transition from use to SUD and the speed with which this may occur at the population level, with a focus on the impact of pre-existing mental disorders.

METHODS

Data were collected as part of the 2007 Australian National Survey of Mental Health and Wellbeing, a nationally representative survey of 8841 Australian adults. A series of discrete time survival analyses were undertaken on data pertaining to the age of onset of use and symptoms of use disorder, for alcohol, cannabis, sedatives, stimulants, and opioids, as well as the impact of pre-existing mood and anxiety disorders on the likelihood of developing a SUD.

RESULTS

Lifetime cumulative probability estimates indicated that 50.4% of stimulant, 46.6% of opioid, 39% of sedative, 37.5% of alcohol, and 34.1% of cannabis users would develop a SUD on those substances, within an estimated 14, 12, 8, 30, and 23 years after onset respectively. Pre-existing mental disorders were significantly associated with increased risk of developing a SUD for alcohol, cannabis and stimulant use disorder.

CONCLUSION

The relative speed associated with the transition from use to SUD emphasizes the narrow window of time available to intervene, underscoring the urgency of early identification of mental health conditions and the timely provision of appropriate evidence-based interventions, which could potentially prevent the development of secondary SUDs.

Shaping vulnerability to addiction - the contribution of behavior, neural circuits and molecular mechanisms

Substance use disorders continue to impose increasing medical, financial and emotional burdens on society in the form of morbidity and overdose, family disintegration, loss of employment and crime, while advances in prevention and treatment options remain limited. Importantly, not all individuals exposed to abused substances effectively develop the disease. Genetic factors play a significant role in determining addiction vulnerability and interactions between innate predisposition, environmental factors and personal experiences are also critical. Thus, understanding individual differences that contribute to the initiation of substance use as well as on long-term maladaptations driving compulsive drug use and relapse propensity is of critical importance to reduce this devastating disorder. In this paper, we discuss current topics in the field of addiction regarding individual vulnerability related to behavioral endophenotypes, neural circuits, as well as genetics and epigenetic mechanisms. Expanded knowledge of these factors is of importance to improve and personalize prevention and treatment interventions in the future.

Estimated probability of becoming a case of drug dependence in relation to duration of drug-taking experience: a functional analysis approach

Measured as elapsed time from first use to dependence syndrome onset, the estimated "induction interval" for cocaine is thought to be short relative to the cannabis interval, but little is known about risk of becoming dependent during first months after onset of use. Virtually all published estimates for this facet of drug dependence epidemiology are from life histories elicited years after first use. To improve estimation, we turn to new month-wise data from nationally representative samples of newly incident drug users identified via probability sampling and confidential computer-assisted self-interviews for the United States National Surveys on Drug Use and Health, 2004-2013. Standardized modules assessed first and most recent use, and dependence syndromes, for each drug subtype. A four-parameter Hill function depicts the drug dependence transition for subgroups defined by units of elapsed time from first to most recent use, with an expectation of greater cocaine dependence transitions for cocaine versus cannabis. This study's novel estimates for cocaine users one month after first use show 2-4% with cocaine dependence; 12-17% are dependent when use has persisted. Corresponding cannabis estimates are 0-1% after one month, but 10-23% when use persists. Duration or persistence of cannabis smoking beyond an initial interval of a few months of use seems to be a signal of noteworthy risk for, or co-occurrence of, rapid-onset cannabis dependence, not too distant from cocaine estimates, when we sort newly incident users into subgroups defined by elapsed time from first to most recent use. Copyright © 2016 John Wiley & Sons, Ltd.

Marijuana use disorder symptoms among recent onset marijuana users

BACKGROUND

With recreational marijuana having recently been legalized in a growing number of U.S. states, as well as the increasing support for its legalization among substantial segments of the American public, an understanding of the development of symptoms associated with marijuana use disorders will assist in guiding both education and policy.

METHODS

This study examined the prevalence of marijuana use disorder symptoms among a nationally representative sample of recent onset marijuana users ages 12-21 drawn from the National Survey of Drug Use and Health (N=9697).

RESULTS

The most frequently reported marijuana use symptoms were "tolerance", and "time occupied acquiring, using or recovering from the effects of marijuana". Logistic regression analyses indicated an expected positive association between marijuana use frequency and each marijuana use disorder symptom. In many cases the positive trend was quadratic or cubic, with greater increases between rates among low and moderate frequency marijuana users (i.e. 1-10days per month) than among those using at a higher frequency (i.e. >10days per month). Relationships between marijuana use frequency and marijuana use symptoms were largely consistent according to age, gender and ethnicity.

CONCLUSIONS

Recognizing symptoms of marijuana use disorders among adolescents and young adults using marijuana infrequently may assist in early identification and intervention for those at risk for problem use.

Cannabis Epidemiology: A Selective Review

BACKGROUND

Globally, the most widely used set of compounds among the internationally regulated drugs is cannabis.

OBJECTIVE

To review evidence from epidemiological research on cannabis, organized in relation to this field's five main rubrics: quantity, location, causes, mechanisms, and prevention/ control.

METHOD

The review covers a selection of evidence from standardized population surveys, official statistics, and governmental reports, as well as published articles and books identified via MEDLINE, Web of Science, and Google Scholar as of July 2016.

RESULTS

In relation to quantity, an estimated 3% to 5% of the world population is thought to have tried a cannabis product, with at least one fairly recent use, mainly extra-medical and outside boundaries of prescribed use. Among cannabis users in the United States, roughly one in 7-8 has engaged in medical marijuana use. In relation to location, prevalence proportions reveal important variations across countries and between subgroups within countries. Regarding causes and mechanisms of starting to use cannabis, there is no compelling integrative and replicable conceptual model or theoretical formulation. Most studies of mechanisms have focused upon a 'gateway sequence' and person-to-person diffusion, with some recent work on disability-adjusted life years. A brief review of cannabis use consequences, as well as prevention and control strategies is also provided.

CONCLUSION

At present, we know much about the frequency and occurrence of cannabis use, with too little replicable definitive evidence with respect to the other main rubrics. Given a changing regulatory environment for cannabis products, new institutions such as an independent International Cannabis Products Safety Commission may be required to produce evidence required to weigh benefits versus costs. It is not clear that governmentsponsored research will be sufficient to meet consumer demand for balanced points of view and truly definitive evidence.

Rapid transition from drinking to alcohol dependence among adolescent and young-adult newly incident drinkers in the United States, 2002-2013

BACKGROUND

To study male-female and age differences in estimates of rapid transition from first full drink to alcohol dependence among youthful newly incident drinkers in the United States (US).

METHOD

The study population included 12-to-25-year-old non-institutionalized US civilian residents, sampled for US National Surveys on Drug Use and Health 2002-2013, with assessments via confidential computer assisted self-interviews. Newly incident drinkers are those who had their first full drink soon before the assessment (n=32,562 12-to-25-year- olds). Alcohol dependence (AD) criteria are from DSM-IV.

RESULTS

For 12-to-25-year-old females, the peak risk for making a rapid transition from first full drink to alcohol dependence is seen during adolescence, followed by declining estimates (meta-analysis summary=3% at 12-17 years of age, 95% CI=2%, 3%). Among males, corresponding estimates fluctuate around 2%, with no appreciable differences across age strata. Among 12-to-17-year-old newly incident drinkers, there is a female excess in the rapid transition to alcohol dependence; a male excess is observed among young adult newly incident drinkers. Evaluated cohort-wise, using an epidemiological mutoscope view, individual cohorts show a congruent pattern, with age at first drink held constant.

CONCLUSIONS

Studying multiple replication samples of young newly incident drinkers, we discovered a clear female excess in the risk of a rapid transition from first full drink to alcohol dependence among adolescents, with age patterns differing across males and females.

Inter-relationships Linking Probability of Becoming a Case of Nicotine Dependence With Frequency of Tobacco Cigarette Smoking

INTRODUCTION

Once smoking starts, some tobacco cigarette smokers (TCS) can make very rapid transitions into tobacco dependence syndromes (TCD). With adjustment for smoking frequency, we posit female excess risk for this rapid-onset TCD. In a novel application of functional analysis for tobacco research, we estimate four Hill function parameters and plot TCD risk against a gradient of smoking frequency, as observed quite soon after smoking onset.

METHODS

In aggregate, the National Surveys of Drug Use and Health, 2004-2013, identified 1546 newly incident TCS in cross-sectional research, each with standardized TCD assessment.

RESULTS

Hill function estimates contradict our apparently over-simplistic hypothesis. Among newly incident TCS males with only 1-3 recent smoking days, an estimated 1%-3% had become rapid-onset TCD cases; non-overlapping confidence intervals show lower TCD risk for females. In contrast, among daily smokers, closer to 50% of female TCS showed rapid-onset TCD, versus under 20% of male TCS, but a larger sample will be needed to confirm the apparent female excess risk at the daily smoking frequency level.

CONCLUSIONS

Smoking frequency and TCD onset become inter-dependent quite soon after TCS onset. Feedback loops are expected, and might explain a potential reversal of male-female differences across smoking frequency gradients. These novel epidemiological estimates prompt new thinking and questions about interventions.

IMPLICATIONS

In this large sample epidemiological study, with a nationally representative sample of newly incident TCS assessed cross-sectionally, we see a quite rapid onset of tobacco dependence, with an early male excess that fades out at higher levels of smoking frequency. Next steps include development of outreach and intervention for this very rapid-onset tobacco dependence.

Does our legal minimum drinking age modulate risk of first heavy drinking episode soon after drinking onset? Epidemiological evidence for the United States, 2006-2014

Background. State-level 'age 21' drinking laws conform generally with the United States National Minimum Drinking Age Act of 1984 (US), and are thought to protect young people from adverse drinking experiences such as heavy episodic drinking (HED, sometimes called 'binge drinking'). We shed light on this hypothesis while estimating the age-specific risk of transitioning from 1st full drink to 1st HED among 12-to-23-year-old newly incident drinkers, with challenge to a "gender gap" hypothesis and male excess described in HED prevalence reports. Methods. The study population consisted of non-institutionalized civilians in the United States, with nine independently drawn nationally representative samples of more than 40,000 12-to-23-year-olds (2006-2014). Standardized audio computer-assisted self-interviews identified 43,000 newly incident drinkers (all with 1st HED evaluated within 12 months of drinking onset). Estimated age-specific HED risk soon after first full drink is evaluated for males and females. Results. Among 12-to-23-year-old newly incident drinkers, an estimated 20-30% of females and 35-45% of males experienced their 1st HED within 12 months after drinking onset. Before mid-adolescence, there is no male excess in such HED risk. Those who postponed drinking to age 21 are not spared (27% for 'postponer' females; 95% CI [24-30]; 42% for 'postponer' males; 95% CI [38-45]). An estimated 10-18% females and 10-28% males experienced their 1st HED in the same month of their 1st drink; peak HED risk estimates are 18% for 'postponer' females (95% CI [15-21]) and 28% for 'postponer' males (95% CI [24-31]). Conclusions. In the US, one in three young new drinkers transition into HED within 12 months after first drink. Those who postpone the 1st full drink until age 21 are not protected. Furthermore, 'postponers' have substantial risk for very rapid transition to HED. A male excess in this transition to HED is not observed until after age 14.